Add TCM data access page (#4322)

Resolves #3899, #4253

Author: p7nov

doc/reference/tooling/tcm/index.rst

@@ -40,6 +40,7 @@ to read data. LDAP authorization is supported as well.
     tcm_cluster_config
     tcm_cluster_monitoring
     tcm_cluster_metrics
+    tcm_cluster_data_access
     tcm_access_control
     tcm_audit_log
     tcm_configuration

doc/reference/tooling/tcm/tcm_cluster_data_access.rst

@@ -0,0 +1,126 @@
+..  _tcm_cluster_data_access:
+
+Accessing cluster data
+======================
+
+..  include:: index.rst
+    :start-after: ee_note_tcm_start
+    :end-before: ee_note_tcm_end
+
+|tcm_full_name| provides access to data stored in connected clusters through its
+web interface. You can view, add, edit, and delete tuples from spaces.
+
+.. note::
+
+    A |TCM| user's access to specific clusters and spaces is determined by their
+    :ref:`cluster permissions <tcm_access_control_permissions>` and :ref:`access control list <tcm_access_control_acl>`.
+
+Data access is implemented in |tcm| on a per-instance basis: you can access
+data stored on one cluster instance at a time. For sharded clusters that use the
+`CRUD <https://github.com/tarantool/crud>`__ module,
+it's also possible to access data throughout the whole cluster.
+
+..  _tcm_cluster_data_access_instance:
+
+Instance data
+-------------
+
+There are the following ways to access data stored on a cluster instance from |tcm|:
+
+-   **Instance explorer** displays the instance's spaces as tables in the web interface
+-   **SQL terminal** allows executing SQL statements on the instance
+-   **Tarantool and tt consoles** allow accessing the data using the Lua API
+
+.. important::
+
+    Data modification is possible only on instances in the read-write mode (replica set leaders).
+    Changes are applied to read-only replicas in accordance with the cluster topology.
+
+..  _tcm_cluster_data_access_instance_explorer:
+
+Instance explorer
+~~~~~~~~~~~~~~~~~
+
+The instance explorer provides access to all spaces that exist on the instances
+in the web interface. This includes both system and user spaces.
+
+To open the instance explorer:
+
+#.  Go to **Stateboard**.
+#.  Click the instance row in the instances list or its graph vertex in the graph view.
+#.  Click **Explorer** in the **Actions menu** of the instance details page.
+
+To view tuples of a space, click its row in the spaces list.
+
+To add a new tuple, click **+** on the space page and provide tuple field values
+in the Lua format, for example, ``[ 1, 1000, true, "test"]``.
+
+To edit a tuple, click it in the table and then click **Edit**.
+
+To delete a tuple, select it in the table and click **Delete** (the trash bin button).
+
+In the development mode, you can also create, edit, truncate, and delete spaces
+in the instance explorer. To create a space, click **Add** and follow the wizard steps.
+To edit, truncate, or remove a space, click the corresponding button in the **Actions**
+menu of the space row in the table.
+
+..  _tcm_cluster_data_access_instance_sql:
+
+SQL terminal
+~~~~~~~~~~~~
+
+|tcm| features an SQL terminal that you can use to access stored data. It is located
+on the **SQL** tab of the instance details page. In the SQL terminal, you can execute
+any :ref:`supported SQL expressions <sql_statements_and_clauses>` on the selected instance.
+
+For ``select`` SQL queries, you can also download the query result set in the CSV format.
+
+To learn more about using SQL in Tarantool, see the :ref:`sql_tutorial`.
+
+..  _tcm_cluster_data_access_instance_lua:
+
+Lua API: Tarantool and tt consoles
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+|tcm| provides interactive access to instances' consoles on the **Terminal** tab
+of the instance details page. You can choose between the :ref:`tt console <tt-interactive-console>`
+(**TT Connect** tab) and :ref:`Tarantool interactive console <interactive_console>` (**Direct** tab).
+
+In these consoles, you can access the stored data using the Tarantool :ref:`Lua API <built_in_modules>`.
+
+..  _tcm_cluster_data_access_crud:
+
+Sharded cluster data
+--------------------
+
+For sharded clusters that use the `CRUD <https://github.com/tarantool/crud>`__ module,
+it's possible to access stored data throughout the cluster on the **Cluster** > **Tuples** page.
+This page displays only user spaces.
+
+To view all tuples of a space in a sharded cluster, click the space row in the list.
+
+To add a new tuple, click **+** on the space page and provide tuple field values
+in the Lua format, for example ``[ 1, 1000, true, "test"]``. When you add a tuple
+in a sharded cluster, it is distributed to a replica set based on the sharding key
+(the ``bucket_id`` field) value.
+
+To edit a tuple, click it in the table and then click **Edit**.
+
+To delete a tuple, select it in the table and click **Delete** (the trash bin button).
+
+
+..  _tcm_cluster_data_access_crud_spaces:
+
+Creating spaces in sharded clusters
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+To create a space in a sharded cluster, create it on all read-write cluster instances
+on their :ref:`Instance explorer <tcm_cluster_data_access_instance_explorer>` pages.
+
+.. important::
+
+    Sharded spaces must include the ``bucket_id`` field of the ``unsigned`` type
+    and a non-unique index by this field with the same name.
+
+To edit, truncate, or delete spaces in a sharded cluster, perform the corresponding
+action on all read-write cluster instances.